Important Questions with answers

Chapter 7 – Control and Coordination

Question 1: State the function of any three of the structural and functional unit of nervous system. Answer 1: Nervous system: Main parts of nervous system are: (i) Central nervous system, (ii) Peripheral nervous system, (iii) Autonomous System. (i) Central Nervous System: It consist of (a) Brain receives information carrying impulses from all the sensory organs (by sensory nerves) of the body and also from the spinal cord. The brain respond to the information by sending its own instructions (through motor nerves) to the muscles and glands to act accordingly. The brain also stores information and act as organ of thought and intelligence. (b) Spinal cord: It is concerned with spinal reflex actions and the conduction of nerve impulses to and from the brain. (ii) Peripheral Nervous system: it is composed of cranial nerves (nerves from the brain) and the spinal nerves. Both of these consist of sensory and motor neurons. So, they carry sensations to and messages from the brain and the spinal cord. (iii) Autonomous Nervous System: It is that part of the peripheral nervous system which controls the activities of the internal organs such as stomach, heart-beat, etc. automatically even without our thinking about them. Its nerves are attached to the smooth muscles and control the activities of internal organs of the body involuntarily, many these nerves are connected with the mid- brain and hind-brain.

Question 2: How does over production of hormones controlled? Give one example. Answer 2: Endocrine glands or ductless glands produce hormones and directly pour their secretion in the blood. These glands do not go on producing hormones. Their secretion is controlled by feedback information system. Thus their over production of hormones is controlled. For example, a hormone called TSH is secreted by pituitary gland. TSH stimulates the production of thyroxine from the thyroid gland. But if there is over production of thyroxine hormone, this hormone acts on pituitary gland and controls the production of TSH. As a result, the production of thyroxine by the thyroid gland is controlled. Thus, TSH and thyroxine control the level of each other. This mechanism of opposing effect is called feedback mechanism.

Question 3: (a) If the cerebellum is not functioning properly, state the activities of our body that are affected. (b) how do muscles move? Answer 3: (a) Cerebellum is not functioning properly may affect- (i)Walking in straight line (ii)Riding a cycle (iii)Maintaining the posture and balance of the body (iv)Movement is very coordinate, the patient sways in walking and tend to fall towards the affected side. (v)It is responsible for precision of voluntary actions. (b) When the decision to move is conveyed by a nerve to a muscle, it has to act. In response to nervous electrical impulses. The special proteins of the muscle change both their shape and their arrangement in the cell. This new arrangement of these proteins give the muscle cells a shorter form that causes movement of the muscle.

Question 4: (i) Differentiate between sensory neurons and motor neurons. (ii) How is brain protected in our body? (iii)Name the part of the brain responsible for precision of voluntary action and maintaining body posture and balance of the body. Answer 4: (i) Sensory neurons carry sensory impulse from receptors to the nerve cell body or to the region which receives sensory impulses. Whereas motor neurons carry information of action to be carried by the conserved voluntary muscles. (ii) Human brain is lodged in a bony case, the cranium which protects it from injuries. It is wrapped in three sheets of connective tissue, known as meninges. The space between the meninges is filled with cerebrospinal fluid which helps in absorption of shocks. (iii) Fore-brain is responsible for precision of voluntary action. Cerebellum is responsible for maintaining the posture and keeping balance of the body.

More Questions for Exams

Question 1: What is the role of the brain in reflex action? Answer 1: Reflex actions are controlled by spinal cord, although the information input also goes on to reach the brain. However, conditioned reflexes (based on previous experiences), such as salivation after seeing good food are controlled by cerebral cortex of brain.

Question 2: How does adrenaline help an athlete to prepare for running? Answer 2: Adrenaline causes the heart beat faster, resulting in supply of more oxygen. It causes reduction in supply of blood to the digestive system and skin. This diverts the blood to our skeletal muscle. The breathing rate also increases. All these responses together help an athlete to prepare for running.

Question 3: “Use of iodised salt is essential”. List three reasons to justify this statement. Answer 3: (i) Iodised salt supplies sufficient amount of iodine through our diet, even in the areas where iodine is not available naturally through water or otherwise in diet. (ii) Iodine is necessary for the thyroid glands to make thyroxine hormone. (iii) Proper supply of iodine maintains thyroxine level that regulates carbohydrate, protein, and fat metabolism to provide the best balance for growth. (iv) Deficiency of iodine causes many diseases such as Goitre.

Question 4: What is meant by Tropic movement? Why do tropic movements takes place in plants? Answer 4: The directional (tropic) response of plants shown by the plants towards or away of the stimulus such as light, water, gravity, etc. is known as tropism. Tropic movements in plants are growth related. Plants respond to stimuli slowly by growing in a particular direction, either towards stimulus or away from. This growth causing tropic movement is regulated by the plant hormone called auxin.